Magnetic random access memory with switching assist layer

ABSTRACT

A STTMRAM element includes a magnetization layer made of a first free layer and a second free layer, separated by a non-magnetic separation layer (NMSL), with the first and second free layers each having in-plane magnetizations that act on each other through anti-parallel coupling. The direction of the magnetization of the first and second free layers each is in-plane prior to the application of electrical current to the STTMRAM element and thereafter, the direction of magnetization of the second free layer becomes substantially titled out-of-plane and the direction of magnetization of the first free layer switches. Upon electrical current being discontinued to the STTMRAM element, the direction of magnetization of the second free layer remains in a direction that is substantially opposite to that of the first free layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/289,372, filed on Nov. 4, 2011, by Yuchen Zhou, and entitled“MAGNETIC LATCH MAGNETIC RANDOM ACCESS MEMORY (MRAM)”, which is acontinuation-in-part of previously-filed U.S. patent application Ser.No. 13/035,857, filed on Feb. 25, 2011, by Zhou et al., and entitled“Magnetic Latch Magnetic Random Access Memory (MRAM), which claimspriority from previously-filed U.S. Provisional Application No.61/391,263, filed on Oct. 8, 2010, by Huai et al. and entitled “MagneticLatch Magnetic Random Access Memory (MRAM)”.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spin-transfer torque (STT) magneticrandom access memory (MRAM), and, more particularly, to an STTMRAMelement having magnetic tunnel junctions (MTJs) with a multi-layeredfree layer.

2. Description of the Prior Art

Magnetic random access memory (MRAM) is a type of non-volatile memory inwhich magnetization of magnetic layers in MTJs switches between parallel(corresponding to a low resistance state) and anti-parallel(corresponding to high resistance state) configurations. One type ofMRAM is spin-transfer torque magnetic random access memory (STTMRAM)where switching occurs through the application of spin polarized currentacross the MTJ during programming.

STTMRAM has significant advantages over magnetic-field-switched (toggle)MRAM, which has been recently commercialized. The main hurdlesassociated with field-switched-MRAM are its more complex cellarchitecture with high write current (currently in the order ofmilliamps (mA)) and poor scalability attributed to the process used tomanufacture these devices. That is, these devices cannot scale beyond 65nanometer (nm) process node. The poor scalability of such devices isintrinsic to the field writing methods. The current generated fields towrite the bits increase rapidly as the size of the MTJ elements shrink.STT writing technology allows directly passing a current through theMTJ, thereby overcoming the foregoing hurdles and resulting in muchlower switching current [in the order of microamps (uA)], simpler cellarchitecture which results in a smaller cell size (for single-bit cells)and reduced manufacturing cost, and more importantly, improvedscalability.

FIG. 1 shows a prior art STTMRAM element 10 having an anti-ferromagnetic(AFM) layer 6 on top of which is shown formed the a pinned layer (PL)(also known as a “fixed layer”) 5 on top of which is shown formed anexchange coupling layer 4 on top of which is shown formed a referencelayer (RL) 3 on top of which is shown formed a barrier layer (BL, alsoknown as a “tunnel layer” or a “MTJ junction layer”) 2 on top of whichis shown formed a free layer (FL) (also known as a “storage layer (SL)”)1. The layers 3-5 are typically referred to as “syntheticantiferromagnetic” (SAF) structure and generally used for providingreference to the free layer 1 during spin torque (ST) switching of theFL 1 and reading of the state of the FL 1 through the resistance downand across the element 10. The exchange coupling layer (ECL) 4 istypically made of ruthenium (Ru).

When electrons flow across the element 10, perpendicular to the filmplane from the RL 3 to the FL 1, ST from electrons transmitted from theRL 3 to the FL 1 can orientate storage layer or free layer magnetization(as shown by the direction of the arrows in FIG. 1) to a directionparallel to that of RL 3. When electrons flow from the FL 1 to the RL 3,ST from electrons reflected from the RL 3 back into the FL 1 canorientate SL magnetization in a direction that is anti-parallel relativeto that of RL 3. With controlling electron (current) flow direction, SLmagnetization direction can be switched. Resistance across the element10 changes between low and high resistance states when the magnetizationof the FL 1 is parallel or anti-parallel relative to that of RL 3.However, the problem with the element 10 as well as other prior artSTTMRAM elements is that the level of electric current required toswitch the magnetization orientation of FL 1 between parallel andanti-parallel relative to that of RL 3 is still higher than a typicalsemiconductor CMOS structure can provide, therefore making prior artSTTMRAMs' applicability to storage systems not practical.

What is needed is a STTMRAM element that can switch at lower currentwhile still maintaining the same level of stability against thermalagitation.

SUMMARY OF THE INVENTION

Briefly, an embodiment of the invention includes a spin-transfer torquemagnetic random access memory (STTMRAM) element is configured to store astate when electrical current is applied thereto. The STTMRAM elementincludes a fixed layer with a magnetization pinned in the plane of thefixed layer and a barrier layer formed on top of the fixed layer. TheSTTMRAM element further includes a junction layer (JL), and amagnetization layer disposed between the barrier layer and the JL. Themagnetization layer is made of a first free layer and a second freelayer, separated by a non-magnetic separation layer (NMSL), with thefirst and second free layers each having in-plane magnetizations thatact on each other through anti-parallel coupling. Further included inthe STTMRAM element is a perpendicular reference layer (PRL) formed ontop of the JL with magnetization in a direction perpendicular to themagnetization of the fixed layer. The PRL includes two pinned layersseparated by a top separator layer. The direction of the magnetizationof the first and second free layers each is in-plane prior to theapplication of electrical current to the STTMRAM element and after theapplication of electrical current to the STTMRAM element, the directionof magnetization of the second free layer becomes substantially titledout-of-plane and the direction of magnetization of the first free layerswitches. Upon electrical current being discontinued to the STTMRAMelement, the direction of magnetization of the second free layer remainsin a direction that is substantially opposite to that of the first freelayer.

These and other objects and advantages of the present invention will nodoubt become apparent to those skilled in the art after having read thefollowing detailed description of the various embodiments illustrated inthe several figures of the drawing.

IN THE DRAWINGS

FIG. 1 shows a prior art STTMRAM element 10.

FIG. 2 shows relevant layers of a STTMRAM 20 in accordance with anembodiment of the present invention.

FIG. 3(A) shows the state of the element 20 changing from a parallelmagnetic orientation to an anti-parallel magnetic orientation.

FIG. 3(B) shows the state of the element 20 changing from ananti-parallel magnetic orientation to a parallel magnetic orientation.

FIG. 4(A) shows the state of the element 20 during the witching of theFL 24 from a parallel to an anti-parallel orientation relative to the RL21.

FIG. 4(B) shows the state of the element 20 during the switching of theFL 24 from an anti-parallel to a parallel orientation relative to the RL21.

FIG. 5 shows the simulated hard axis transfer curves of a prior artSTTMRAM element and a STTMRAM element of the various embodiments of thepresent invention, such as the element 20.

FIGS. 6(A) and 6(B) show the actual magnetizations of the free layers at45 degree state point for S1 (prior art) and S2 (t1=t2=1.5 nm, d=0.5nm), where S2 has 60% higher Hk value than S1.

FIG. 6(A) shows the magnetization state of S1 single layer at 45 degreestate.

FIGS. 6(B) and 6(C) show the magnetization states of layers 24 and 28 atS2 tri-layer at 45 degree state.

FIG. 7 shows the delta vs. total layer thickness for both the prior artsingle layer and current invention tri-layer designs.

FIG. 8 shows two graphs, 80 and 82, comparing the switching stability ofa STTMRAM element of the embodiments of the present invention that donot include the materials and thicknesses indicated of the FL 28 vs. theswitching stability of the STTMRAM element of the embodiments of thepresent invention that do include the materials and thicknessesindicated herein of the FL 28.

FIG. 9 shows a STTMRAM element 90, which essentially includes the layersof the element 20, in a different order, in accordance with anotherembodiment of the present invention.

FIGS. 10-11 show the switching process exhibited by the element 90 ofFIG. 9.

FIG. 12 shows a STTMRAM element 300, in accordance with anotherembodiment of the present invention.

FIG. 13 shows a STTMRAM element 320, in accordance with anotherembodiment of the present invention.

FIG. 14 shows a STTMRAM element 340, in accordance with anotherembodiment of the present invention.

FIG. 15 shows a STTMRAM element 360, in accordance with anotherembodiment of the present invention.

FIG. 16 shows a STTMRAM element 380, in accordance with anotherembodiment of the present invention.

FIG. 17 shows a STTMRAM element 400, in accordance with anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description of the embodiments, reference is made tothe accompanying drawings that form a part hereof, and in which is shownby way of illustration of the specific embodiments in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized because structural changes may be madewithout departing from the scope of the present invention. It should benoted that the figures discussed herein are not drawn to scale andthicknesses of lines are not indicative of actual sizes.

In the various STTMRAM elements to follow, a MTJ is employed withperpendicular magnetic anisotropy material(s) with improved stability innon-writing modes and easier switching during writing mode.

FIG. 2 shows relevant layers of a STTMRAM element 20 in accordance withan embodiment of the present invention. The STTMRAM element 20 is shownto include a fixed layer (sometimes referred to herein as a “referencelayer (RL)”) 21 on top of which is shown formed a barrier layer(sometimes referred to as a “tunneling layer”) 22 on top of which isshown formed a free layer (FL) 24 on top of which is shown formed anon-magnetic separation layer (NMSL) 26 on top of which is shown formeda free layer 28 on top of which is shown formed a junction layer (JL) 30on top of which is formed a perpendicular reference layer (PRL) 32. Itis understood that the fixed layer 21 is generally formed on top of asubstrate with intervening layers therebetween, such as a seed layer, abottom electrode and other magnetic and non-magnetic layers. The NMSL 26may be metal or non-metal but is a non-magnetic layer that preventsexchange coupling between its two adjacent layers, the FL 24 and the FL28. The FL NMSL 26 and FL 28 are collectively considered a free layer(or “magnetization layer”) in some embodiments where the free layer is amulti-layered structure. In other embodiments, the free layer mayinclude the same pattern of materials repeated numerous times. Forexample, the free layer may have a FL/NMSL/FL/NMSL/FL structure.

Arrows 131 and 132 show the direction of anisotropy in the FL 28, invarious embodiments. For example, the arrow 131 shows the FL 28 to takeon a perpendicular anisotropy and the arrow 132 shows the FL 28 to takeon an in-place anisotropy relative to the plane of the film

BL 22 is an insulation layer whose resistance changes when the relativemagnetization orientations of its two adjacent layers, the FL 22 and thefixed layer 21, change.

In another embodiment, the JL 30 is another barrier layer and in someembodiments, it is made of aluminum (Al) oxide or manganese (Mg) oxideor a conductive layer with Giant Magnetoresistance (GMR) effect betweenFL 28 and PRL 32. Electrons flowing between FL 28 and the PRL 32 carryspin torque effect as well and will cause magnetic change on the FL 28due to spin transfer effects from the PRL 32.

NMSL 26 mainly creates spatial separation between the FL 24 and the FL28. No or very weak spin transfer effect between the FL 24 and the FL 28exists through the NMSL 26.

At non-writing state or when the STTMRAM element 20 is not being writtento, the magnetizations of the FL 24 and the FL 28 are anti-parallel andcouple to each other through magneto-static coupling field from theedges of these two layers. This coupling enhances thermal stabilityduring non-switching state and increases data retention capability. Withadditional in-plane anisotropy in the FL 28, the thermal stability ofthe tri-layer structure, FL 24/NMSL 26/FL 28, can be further enhanced.Such anisotropy is realized either from shape anisotropy or fromcrystalline anisotropy.

FL 28 can also have a certain perpendicular-to-film plane anisotropy sothat when under perpendicular direction spin torque or external fieldmagnetization can further rotate out of plane or even oscillationin-plane due to the perpendicular anisotropy axis.

Exemplary materials of which the various layers of the STTMRAM 20 can bemade with various associated thicknesses and various characteristics arepresented below:

PRL 32:

-   -   Characteristic: Intrinsic perpendicular anisotropy    -   Examplary materials in the case where PRL 32 is a single layer:        iron platinum alloy FePtXY, where X and Y each represent a        material with X being any of the following materials: boron (B),        phosphorous (P), carbon (C), nitride (N) and Y being any of the        materials: Cobolt (Co), tantalum (Ta), titanium (Ti), niobium        (Nb), zirconium (Zr), tungsten (W), silicon (Si), copper (Cu),        silver (Ag), aluminum (Al), chromium (Cr), tin (Sn), lead (Pb),        antimony (Sb), hafnium (Hf) and bismuth (Bi), molybdenum (Mo) or        ruthenium (Ru).    -   Alternative Characteristic: Interfacial effect inducing        perpendicular magnetic anisotropy    -   Examplary materials in the case where PRL 32 is made of alloys:        Fe-rich FeCoXY or FeNiXY alloys, or alloys CoNiXY.    -   In the case where PRL 32 is made of multiple layers, exemplary        materials are as follows:        -   [Co/Pt]n, [Co/Pd]n, [Co/Ni]n,        -   Amorphous ferrimagnetic alloys, such as TbFeCo, GdFeCo

JL 30:

-   -   Non-magnetic metals copper (Cu), silver (Ag), gold (Au);    -   Non-magnetic materials, aluminum oxide (Al2O3), zinc oxide        (ZnO), magnesium oxide (MgO)

FL 28:

-   -   The FL 28 may be made of alloys, such as FeCoXY, FeNiXY, or        CoNiXY. The perpendicular anisotropy is tuned while keeping the        equilibrium orientation in-plane.    -   An alloy of one or more of the following material may also        comprise the FL 28: iron (Fe), nickel (Ni), cobalt (Co),        platinum (Pt), copper (Cu), boron (B), tantalum (Ta), titanium        (Ti), chromium (Cr), niobium (Nb), vanadium (V), zirconium (Zr),        terbium (Tb), samarium (Sm), neodymium (Nd), and gadolinium        (Gd). May also be comprised of one or more of silicon dioxide        (SiO2), titanium dioxide (TiO2), tantalum oxide (Ta2O5), and        aluminum oxide (Al2O3).    -   In other embodiment, the FL 28 is made of magnetic alloys, such        as CoFeB-X, where ‘X’ is chosen from the elements having low        emissivity into Co and/or Fe, by using one or more of the        following elements: Cr, Cu, Ta, Ti, Mo, P, N, and 0. ‘X’, in        some embodiments, is less than 25 atomic percentage (at %) of        Cr, Cu or Mo.    -   In yet another embodiment, FL 28 is made of CoFeB-Y, where ‘Y’        is chosen from one or more of the oxides and nitrides, such as,        SiO2, TiO2, Ta2O5, WO, or ZrO2. ‘Y’, in some embodiments, is        less than 20 molar percentage of SiO2 or TiO2.

FL 24:

-   -   An alloy of one or more of iron (Fe), nickel (Ni), cobalt (Co),        platinum (Pt), copper (Cu), boron (B), tantalum (Ta), titanium        (Ti), chromium (Cr), niobium (Nb), vanadium (V), zirconium (Zr),        terbium (Tb), samarium (Sm), neodymium (Nd), and gadolinium        (Gd).

NMSL 26:

-   -   Non-magnetic materials, such as titanium dioxide (TiO2), oxide        (Al2O3), ruthenium oxide (RuO), strontium oxide (SrO), zinc        oxide (ZnO), magnesium oxide (MgO), zirconium dioxide (ZrO2),        titanium (Ti), tantalum (Ta), ruthenium (Ru), magnesium (Mg),        chromium (Cr), niobium (Nb), nickel niobium (NiNb). Non-magnetic        metals copper (Cu), silver (Ag), gold (Au).    -   Alternatively, ‘n’ number of interlaced non-magnetic oxide and        non-magnetic metallic layers may comprise NMSL 26, ‘n’ being an        integer equal or greater than one.

In yet another embodiment, a thin layer, of less than 10 nano meters(nm) in thickness, of Cr, Cu, CrTa, CrTi, CrMo, CrTib, CrZrB, or CrW isdeposited on top of the FL 28 prior to deposition of the JL 30. Duringmanufacturing of the element 20, and specifically the magnetic annealingprocess, the foregoing elements segregate along the grain-boundariesand/or along the defect areas to decouple the magnetic grains of the FL28.

In still another embodiment, a thin layer layer, typically less than 10nm, of Cr, Cu, CrTa, CrTi, CrMo, CrTiB, CrZrB, CrW is deposited in themiddle of the FL 28, during manufacturing of the element 20.

In a yet another embodiment, right after deposition of the FL 28, andbefore deposition of the JL 30, an ion implantation process is carriedout whereby ions of Cr, Mo, Ta, Ti, Zr, are implanted into the FL 28.

In yet another embodiment, a reactive gas is introduced during thedeposition of FL 28. The gas can be chosen from one or more of thefollowing: O2, N2, Co, Co2, No, NO2, SO2, CF4, or CL2. The flow rate ofthe inert gas can be kept constant or changed during deposition of theFL 28.

The foregoing approaches and structures desirably result in theformation of largely magnetic and non-magnetic areas in the FL 28thereby lowering the stiffness of the element 20. In fact, FIG. 8 showsgraphs showing the affect of the foregoing methods and structure on thebehavior of the element 20, as will be discussed shortly below.

It is understood that in various embodiments, any combination of theabove-noted material may be employed.

FIG. 3(A) shows the state of the element 20 changing from a parallelmagnetic orientation to an anti-parallel magnetic orientation. That is,the direction of magnetization of the FL 24 change relative to the RL21. FIG. 3(B) shows the state of the element 20 changing from ananti-parallel magnetic orientation to a parallel magnetic orientation.That is, the direction of magnetization of the FL 24 relative to the RL21.

In FIG. 3(A), at the left side of the figure, the element 20 is shownwith electrons flowing, as indicated by the arrow 25, from FL 28 to thedirection of BL 22. These electrons first flow through PRL 32 and theninto FL 28. Due to these transmitted electrons' spin torque (ST) effectbetween the PRL 32 and the FL 28 through the JL 30, FL 28'smagnetization is further rotated out of plane towards the magnetizationdirection of PRL 32, and can be substantially perpendicular when spintorque is strong enough to allow such perpendicular configuration. Withless in-plane magnetization of FL 28, FL 24 experiences less couplingfield from FL 28 and coupling-induced-stabilization of FL 24 by FL 28 isreduced. Thus, FL 28-to-FL 24 magnetic latching mechanism is released.Magnetic latching (or “latching” as used herein) refers to the processof weaker coupling of the FL 28 to FL 24 allowing easier switching ofthe FL 24. Releasing the latching (or “unlatching” as used herein)refers to the FL 28 coupling to FL 24 to be released. With electronscontinuing to travel from FL 24 to RL 21 through BL 22, reflectedelectrons from RL 21 lead to switching of FL 24 to an anti-parallelstate while FL 28-FL 24 coupling is unlatched.

When FL 24 completes its state switching, electrical current isdiscontinued. Spin torque from PRL 32 to FL 28 now also discontinues. FL28's magnetization rotates back to an in-plane orientation, as shown bythe state of the element 20 on the right side of FIG. 3(A). Due tomagneto-static field from FL 24, when magnetization of the FL 28 rotatesback in-plane, the magnetization of the FL 28 orients anti-parallelrelative to that of FL 24, which is once again in a latchedmagnetization configuration.

In summary, prior to the flow of electrical current through the element20, the direction of magnetization of each of the FLs 24 and 28 issubstantially in-plane and after the application of electrical currentto the element 20, with the electrical current flowing through each ofthe layers thereof, the direction of magnetization of the FL 28 becomestitled out-of-plane, either completely or partially, and the directionof magnetization of the FL 24 switches. When the application ofelectrical current to the element 20 is discontinued, the direction ofmagnetization of the FL 28 remains in a direction that is substantiallyopposite to that of the FL 24.

It is noted that electrical current is applied either from the bottom tothe top of the element 20 or from the top to the bottom of the element20.

With reference to FIG. 3(B), switching of FL 24 from anti-parallel toparallel orientation relative to RL 21 is now explained. An analogousoperation takes place in FIG. 3(B) as that explained relative to FIG.3(A), except that electrons move in the opposite direction, as indicatedby the arrow 25 in FIG. 3(B). Thus, FL 28 experiences reflectedelectrons from PRL 32 when current is applied and rotates out of planeopposite to that magnetization of the PRL 32. FL 28-to-FL 24 coupling isthus unlatched. FL 24 switches its state to a parallel state relative toRL 21 magnetization due to transmitted electrons from RL 21. Onceswitching is completed and current is removed, FL 28 s magnetizationrotates to an in-plane and anti-parallel to the magnetization of FL 24due to the magneto-static coupling field from FL 24.

FIG. 4(A) shows the state of the element 20 during the switching of theFL 24 from a parallel to an anti-parallel orientation relative to the RL21. The arrow 27 shows the direction of electrons as the arrow 25 inFIG. 3(A). FIG. 4(B) shows the state of the element 20 during theswitching of the FL 24 from an anti-parallel to a parallel orientationrelative to the RL 21. The arrow 27 shows the direction of electrons asthe arrow 27 in FIG. 3(B).

The switching process is analogous to that which is described aboverelative to FIGS. 3(A) and 3(B), except that during current application,FL 28 does not just rotate out of plane. Due to the existence of surfacedemagnetization field of FL 28, with possibly a relatively strongperpendicular anisotropy 131 in FL 28, FL 28 in-plane magnetizationcomponent starts to oscillate in-plane and forms aferromagnetic-resonance (FMR) mode, with a magnetization trajectorydepicted as at the left side of FIG. 4(A). Such oscillation can be muchhigher frequency than the switching speed of the FL 24 and thus produceseffectively zero field in the FL 24 from FL 28 over the switchingprocess of the FL 24. Alternatively, magnetization of FL 28 can becomecompletely perpendicular after the initial oscillation state. After FL24 switching and current is removed, FL 28 magnetization relaxes back toin-plane orientation anti-parallel to that of the FL 24 due tomagneto-static coupling field from FL 24.

In FIG. 4(B), the operation of the element 20 is analogous to that ofFIG. 4(A) discussed above except that the direction of the travel ofelectrons is in the opposite direction. Thus, FL 28 experiencesreflected electrons from the PRL 32 when current is applied and rotatesout of plane opposite to the magnetization of the PRL 32 and startsferromagnetic-resonance (FMR) oscillation. FL 28-to-FL 24 coupling isthus unlatched. Alternatively, magnetization of the FL 28 can becomecompletely perpendicular after the initial oscillation state. FL 24switches to a state that is parallel to that of the FL 21 due totransmitted electrons from FL 21. Once switching is complete and currentis removed, FL 28 magnetization rotates back in-plane and anti-parallelto that of FL 24 due to the FL 24's magneto-static coupling field.

Accordingly, the various embodiments of the present invention realizegreater stability than that realized currently by prior art techniquesand as discussed hereinabove, use a tri-layer structure, layers 24-28,where FLs 24 and 28, separated by the NMSL 26, magneto-statically coupleto each other through edge magnetic charges in quiescent state. Suchcoupling makes the tri-layer structure stable against thermal agitation.Meanwhile, it allows for thinner than usual magnetic layers FL 24 and FL28 due to stronger thermal stability. In one embodiment of the presentinvention, the combined thickness of FL 24 and FL 28 is 20% thinner thana single free layer of prior art techniques, at the same thermalstability.

Additionally, with magnetic latching FL 28 mainly affected by spintorque from PRL 32, which is perpendicular in its magnetic state, whilecoupling between layers FL 24 and FL 28 is affected by NMSL 26'sthickness, thermal stability through latching effect and easiness ofswitching with temporarily turning off the latching by spin torque fromthe PRL 32 to the FL 28 can be individually adjusted with much largerspace of optimization than the prior art, where thermal stability andeasiness of switching are tightly bonded due to utilizing a single layerFM2 for the switching and data storage.

FIG. 5 shows the simulated hard axis transfer curves of a prior artSTTMRAM element with a single free layer (switching layer) and a STTMRAMelement of the various embodiments of the present invention, such as theelement 20. An external field is applied to the STTMRAM elementstructure, where a same size elliptical shape with aspect ratio ˜2 andlong axis <200 nm is assumed for all STTMRAM element structures. Thesingle layer case as in FIG. 5 is for the prior art structures with asingle switching layer, i.e. layer 1 in prior art −1 and FM2 layer inprior art −2. Tri-layer cases consider a switching layer structurecomposed of layers 24˜28 as in the embodiments. For the prior art singlelayer case, the switching layer Ms=1000 emu/cc with thickness t=3 nm.For the embodiment tri-layer cases, layer 24 and 28 have Ms=1000 emu/cc,with thickness t1(layer 24)=t2(layer 28) and varying from 1 nm to 1.5nm. The thickness of the spacer layer 26 varies between 0.5 nm and 1 nmin some embodiments. The graph of FIG. 5 shows external field, in thex-axis, vs. the angle of magnetization of the free layer of the variousembodiments of the present invention, in the y-axis. An external fieldof −1 kOe to +1 kOe is applied in the short axis direction of theellipse. The free layer magnetization angle relative to the long axisdirection of the ellipse is plotted vs. the applied field in FIG. 5. Atangle of 45 degree, it is regarded the point where the applied fieldequals intrinsic Hk of the STTMRAM free layer.

From FIG. 5, it is clearly shown that with tri-layer structure, thefield required to reach 45 degree angle is higher than the single layercase. The corresponding Hk values estimated from the transfer curves foreach case is also indicated in the legend of FIG. 5. By varying themagnetic layer thickness and spacer layer thickness of the tri-layerstructure, Hk changes accordingly due to varied coupling strength.However, all cases show a stronger Hk, than single 3 nm layer case as inprior arts, indicating a better thermal stability of the tri-layerstructure.

FIGS. 6(A) and 6(B) show the actual magnetizations of the free layers at45 degree state point for S1 (prior art) and S2 (t1=t2=1.5 nm, d=0.5nm), where S2 has 60% higher Hk value than S1.

In particular, FIG. 6(A) is the magnetization state of S1 single layerat 45 degree state. FIGS. 6(B) and 6(C) are the magnetization states oflayers 24 and 28 at S2 tri-layer at 45 degree state. FIG. 6(A) and FIG.6(B) are quite similar, only that FIG. 6(B) happens at a much higherfield.

FIG. 7 shows the delta (a measurement of thermal stability) vs. totallayer thickness for both the prior art single layer and currentinvention tri-layer designs. The delta value is defined as magneticanisotropy energy of the magnetic layer divided by the thermalexcitation energy, i.e. K_(u)V/k_(B)T=H_(k)M_(s)V/2k_(B)T, where Hkvalues are previously obtained from FIG. 5, M_(S)=1000 emu/cc for allstructures, k_(B) is Boltzmann constant, T is the absolute temperatureof 80 degree Celsius. V for prior art design is the volume of the singleswitching layer, and the combined volume of layers 24 and 28 in theembodiments of the present invention. FIG. 7 shows the delta vs. totallayer thickness for tri-layer structures with spacer layer thickness of0.5 nano meters (nm) and 1 nm. For prior art, only t=3 nm is consideredas reference. From FIG. 7, it is clearly shown that delta for tri-layerdesign at same total magnetic layer thickness is much higher than priorart single layer. Also to reach same as prior art delta, tri-layerthickness can be <2.4 nm, which is more than 20% thinner than prior art.During switching by spin torque, embodiment type of operation unlatcheslayer 28 from coupling to layer 24, and makes switching volume evensmaller than the combined volume. Thus a higher stability and easier toswitching MRAM MTJ is achieved.

FIG. 8 shows two graphs, 80 and 82, comparing the switching stability ofa STTMRAM element of the embodiments of the present invention that donot include the materials and thicknesses indicated of the FL 28 vs. theswitching stability of the STTMRAM element of the embodiments of thepresent invention that do include the materials and thicknessesindicated herein of the FL 28. Each graph has y-axis representing Mx/Ms(switching stabilization) with ‘Mx’ representing the magnetization ofthe free layer in the easy axis, i.e. long axis, and ‘Ms’ representingthe saturation magnetization of the free layer and x-axis representingtime in nano seconds. Graph 80 is the performance of the STTMRAM element20 without the materials and thicknesses noted in the variousembodiments discussed hereinabove at pages 9-12 hereinabove whereasgraph 82 is the performance of the STTMRAM element 20 using thematerials and thicknesses noted in the various embodiments discussedhereinabove at pages 9-12 hereinabove. The line 131 is the switchingbehavior of the FL 28 in real-time and when FL 28 has an in-planemagnetization, as does the line 111 relative to another switching stateof the FL 28. Line 132 is the orientation of the FL 28 during switching,as is line 112 when another switching state takes place. Line 100 is a 5ns pulse starting from lns and ending at 6 ns, applied to the element20. As shown, switching of the FL 28, in graph 82, is far smoother, withless volatility, than that shown in graph 80. Switching stabilizationimprovement desirably causes reduced internal exchange in the FL 28. Itis noted that in graph 80, the FL 28's internal exchange isapproximately 1×10⁻⁶ erg/cm whereas in graph 82, the internal exchangeof the FL 28 is 0.2×10⁻⁶ erg/cm. Accordingly, the graphs of FIG. 8 showreducing the internal exchange of the FL 28, and applying a currentpulse that ends at 6 ns, the FL 24 and the FL 28, having an in-planemagnetization oscillation, effectively eliminate and render finalswitched state of the FL 24 and the FL 28 more stable and repeatable.

FIG. 9 shows a STTMRAM element 90, which essentially includes the layersof the element 20, in a different order, in accordance with anotherembodiment of the present invention. In FIG. 9, the element 90 is shownto have the fixed layer 21, which is formed on a substrate (not shown)and on top of the layer 21, is shown formed the BL 22 on top of which isshown formed the FL 24, on top of which is shown formed the PRL 32, ontop of which is shown formed JL 32, on top of which is shown formed NMSL26 and on top of which is shown formed FL 28. While the direction of thearrows in FIG. 9 show an in-plane magnetization of the element 90, aperpendicular magnetization is contemplated, as shown by the lines 131and 132 of FIG. 8, in the FL 28.

During operation, when current is applied to the element 90, spintransfer torque from the PRL 32 rotates the FL 24 magnetizationpartially out of plane. With reduced in-plane magnetic moment of the FL24, in-plane shape anisotropy of FL 24 reduces and its in-planeswitching by the spin transfer torque from fixed layer 21 becomeseasier. Once FL 24 is switched and current turned off, FL 24 out ofplane magnetization falls back in-plane and magnetizes FL 28 to rotateto opposite direction relative to the FL 24 in-plane magnetization dueto the magnetic field from FL 24 acting on FL 28.

FIGS. 10-11 show the switching process exhibited by the element 90 ofFIG. 9. FIG. 10 shows the element 90 with the direction of magnetizationof the layers 21, 24, 32 and 28, as shown by the respective arrows ineach layer. The direction of magnetization of the FL 24 is tilted up,for easier switching, and titled up in a direction to pointing to theright of the page. When current 92 is applied to the element 90, in thedirection shown, going from FL 28 down to the layer 21, the FL 24switches magnetization direction to point to the left but it stillremains tilted, shown at element 90 in the middle of FIG. 10. However,the direction of magnetization of the FL 28 remains the same. Next, whencurrent 92 is turned off and no longer applied to the element 90, asshown by the element 92 appearing at the right-most of FIG. 10, the FL28 switches magnetization direction due to its coupling with the FL 24.Compared to the MRAM structure without the PRL and JL, the requisiteswitching voltage, in the embodiment of FIG. 9, is lowered by 20%-50%.

FIG. 11 shows the switching process exhibited by the element 90 of FIG.9 but in a direction that is opposite to that of the FIG. 10. In FIG.11, current 94 is shown to be applied in a direction, indicated by thearrow associated with the current 94, going from the layer 21 to the FL28. The FL 28 of the element 90 is initially shown to have amagnetization direction that is opposite to the initial magnetizationdirection of the FL 28 of FIG. 10. The same holds true for themagnetization direction of the FL 24 of FIG. 11 in association with itscounterpart in FIG. 10 with the FL 24 having a tilted-left direction ofmagnetization initially. When current 94 is applied, first, as in FIG.10, the direction of magnetization of the FL 24 switches but thedirection of magnetization of the FL 28 remains the same, as shown atthe element 90 in the middle of the FIG. 11. Subsequently, when current94 is no longer applied to the element 90, as shown at the left-most ofthe FIG. 11, the direction of magnetization of the FL 28 switches.

FIG. 12 shows a STTMRAM element 300, in accordance with yet anotherembodiment of the invention. The element 300 is analogous to the elementof FIG. 2 except that the PRL 32 of FIG. 2 is made of the followingthree layers: a pinned layer (PL) 321 (also referred to as “PL-1 321”),the top separator layer (TSL) 322 and the PL 323 (also referred to as“PL-2 323”). The PL 321 is shown formed on top of the JL 30, the TSL 322is shown formed on top of the PL 321, and the PL 323 is shown formed ontop of the TSL 322. Accordingly, the PRL 32 has a tri-layer structureand comprises the layers 321, 322 and 323. As in the case of theembodiment of FIG. 2, the FL 24, the NMSL 26 and the FL 28 comprise amagnetization layer whose magnetic orientation is switchable during theoperation of the element 300 when electrical current flows therethrough.

In some embodiments, the PL 321 and the PL 323 are each made of magneticmaterial and have perpendicular anisotropy (or magnetic orientation) andtheir magnetic orientation, relative to one another, is anti-parallel,as shown by the direction of the arrows in each of these layers. In someembodiments, the TSL 322 is made of non-magnetic material, such as anynon-magnetic metallic or oxide material. In one embodiment, the TSL 322causes anti-ferromagnetic coupling between the layers 321 and 323. Insome such embodiments, the TSL 322 is made of ruthenium (Ru), copper(Cu), tantalum (Ta), titanium (Ti), nickel oxide (NiO), or magnesiumoxide (Mg0) with a thickness of 0.3 nm to 5 nm.

The combined magneto-static field from the layers 321 and 323 exertedonto the FL 24 and the FL 28 is much smaller (and can be optimized toclose to zero field on both layers) than that which is exerted from thePRL 32 onto the FL 24 and the FL 28 of FIG. 2. Thus, advantageously,switching of the FL 24 and the FL 28 is made easier by the embodiment ofFIG. 12.

The layers shown in and discussed relative to FIG. 12 define the MTJ ofthe element 300.

The operation of the element 300 is analogous to that of the element 20of FIG. 2, including the “latching” and “unlatching” effects describedherein.

As with the various embodiments of the invention, electrical current isapplied, bidirectionally, to the element 300, in a direction that isfrom the bottom of the element 300 to the top thereof and/or the top ofthe element 300 to the bottom thereof, during operation of the element300 to store a particular logical state therein. The magnetizationdirections of the PL 321 and the PL 323 are anti-parallel relative toeach other, the direction of the magnetization of the FL 24 and the FL28 are each generally in-plane prior to the application of electricalcurrent and after the application of electrical current to the element300, the direction of magnetization of the FL 28 becomes titledout-of-plane and the direction of magnetization of the FL 24 switches,and upon electrical current no longer flowing through the element 300,the direction of magnetization of the FL 28 maintains a direction thatis substantially opposite to that of the FL 24.

FIG. 13 shows a STTMRAM element 320, in accordance with anotherembodiment of the present invention. The element 320 uses the samelayers as that of the element 300 except that only one free layer, theFL 24, is employed. That is, the element 320 includes the fixed layer 21on top of which is shown formed the BL 22, on top of which is shownformed the FL 24, on top of which is shown formed the JL 30, on top ofwhich is shown formed the PL 321, on top of which is shown formed theTSL 322, on top of which is shown formed the PL 323 with the layers321-323 forming the PRL. The layers shown in and discussed relative toFIG. 13 define the MTJ of the element 320.

As can be appreciated, due to the use of only one free layer, there isno “latching” as that described herein relative to FIGS. 2 and 12.

FIG. 14 shows a STTMRAM element 340 in accordance with yet anotherembodiment of the present invention. The element 340 is analogous to theelement 300 except that a coupling layer (CL) 301 is introduced toreplace the JL. Namely, the element 340 comprises the CL 301 shownformed between the FL 28 and the PL 321, replacing the JL 30 of element300 and is otherwise analogous to the element 300.

In some embodiments, the CL 301 is made of non-magnetic material, suchas metallic materials or oxides, examples of which include but are notlimited to Ru, Cu, silver (Ag), gold (Au), chromium (Cr), titanium (Ti),tantalum (Ta), manganese (Mn), magnesium oxide (MgO), aluminum oxide(Al2O3), nickel oxide (NiO), titanium oxide (TiO), silicon dioxide(SiO2), or silicon nitrogen (SiN). In the case where the CL 301 includesRu, the thickness of the layer CL 301 determines whether this layer isan anti-ferromagnetic layer or a ferromagnetic layer. For example, inthe case where CL 301 is made of Ru and has a thickness of 0.5 nm orless, the CL 301 is a ferromagnetic material whereas, in the case hereCL 301 is made of Ru and has a thickness of approximately 0.6 nm to 1.0nm, the CL 301 is anti-ferromagnetic. In this respect, the FL 28 and thePL 321 are exchange coupled through the CL 301, either ferromagneticallyor anti-ferromagnetically, as the case may be.

As the case of the element 320, there is no “latching” effect in theelement 340 because there is nearly no or very minimal spin transfertorque effect through the CL 301. The layer 321 (PL-1) couples to thelayer 28 by exchange coupling through CL 301. This coupling makesmagnetization of the FL 28 easier to rotate out of plane duringswitching process and makes the switching of each of the FLs 24, 26 and28 easier.

FIG. 15 shows a STTMRAM element 360 in accordance with anotherembodiment of the present invention. The element 360 is analogous to theelement 320 except that the JL 30 is replaced with the CL 301. Thus, inthe embodiment of FIG. 15, a single FL is employed and no latchingeffect is experienced. The CL is made of the same exemplary materials asdiscussed hereinabove and has the same exchange coupling affect as thatdescribed hereinabove.

FIG. 16 shows a STTMRAM element 380, in accordance with yet anotherembodiment of the present invention. The element 380 is analogous to theelement 340 except that the PL 321 is directly in contact with andformed directly on top of the FL 28 with no intermediate layers inbetween. That is, there is no JL or CL between the FL 28 and the PL 321,in element 380. Accordingly, the coupling between the FL 28 and the PL321 is a directly ferromagnetic exchange coupling. As the case of theelement 380, the “latching” and “unlatching” effects exist because thereremains a certain amount of spin transfer torque effect from the layer321 onto the layer 28. However, the exchange coupling between the layer321 and the layer 28 is a much stronger factor and makes switching ofeach of the FLs 24, 26 and 28 easier.

In light of the direct contact between the FL 28 and the PL 321, theselayers can be viewed as a single layer having an interface layer, withthe interface layer being the FL 28 that has mostly in-plane magneticorientation, and the body or primary part of the layer being PL 321having mostly a perpendicular magnetic orientation.

Some of the characteristics of the embodiment of FIG. 12 are shown inthe graphs of FIGS. 5-8.

FIG. 17 shows a STTMRAM element 400, in accordance with yet anotherembodiment of the present invention. The element 400 is analogous to theelement 360 except that the CL 301 is absent and therefore, the PL 321is formed directly on top of the FL 24 with the coupling of these layersbeing directly ferromagnetically exchange coupled. Similar to theembodiment of FIG. 16, the PL 321 and the FL 24 can be viewed as asingle layer with the interface of this layer being the FL 24 withlargely an in-plane magnetic orientation and the body or primary part ofthis layer being the PL 321 with mostly a perpendicular magneticorientation. It is understood that the FL 24 of the element 400 and theFL 28 of the element 380 are each switchable in their magneticorientation during operation of these elements.

Although the present invention has been described in terms of specificembodiments, it is anticipated that alterations and modificationsthereof will no doubt become apparent to those skilled in the art. It istherefore intended that the following claims be interpreted as coveringall such alterations and modification as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A spin-transfer torque magnetic random accessmemory (STTMRAM) element configured to store a state when electricalcurrent is applied thereto, the STTMRAM element comprising: a. a fixedlayer with magnetization pinned in the plane of the fixed layer; b. abarrier layer formed on top of the fixed layer; c. a free layer (FL)formed on top of the barrier layer and having in-plane magnetization; d.a junction layer (JL) formed on top of the FL; e. a perpendicularreference layer (PRL) formed on top of the JL with magnetization in adirection perpendicular to the magnetization of the fixed layer, the PRLincluding a first pinned layer (PL) and a second pinned layer (PL)separated from one another by a top separator layer (TSL), where themagnetization directions of the first pinned layer and the second pinnedare anti-parallel relative to each other, the direction of themagnetization of the FL being in-plane prior to the application ofelectrical current.
 2. The STTMRAM element, as recited in claim 1,wherein the free layer comprises one or more of the elements: Co, Fe,Ni.
 3. The STTMRAM element, as recited in claim 2, wherein the freelayer further comprises one or more of the elements: B, Ta, Ti, Cr, Hf,Zr, O, Mg, Al, Ru, W, Mn, Si, Pt, Mn, Pd.
 4. The STTMRAM element, asrecited in claim 3, wherein the free layer is made ofcobolt-iron-boron-X (CoFeB-X), where ‘X’ is chosen from a group ofelements having low emissivity into Co and/or Fe.
 5. The STTMRAMelement, as recited in claim 3, wherein the free layer is made ofcobolt-iron-boron-X (CoFeB-X), where ‘X’ is chosen from among a group ofelements: Cr, Cu, Ta, Ti, Mo, P, N, or O.
 6. The STTMRAM element, asrecited in claim 1, wherein the free layer comprises a multi-layerstructure with at least one magnetic layer and the at least one magneticlayer of the multi-layer structure comprising at least one element of:Co, Fe, or Ni.
 7. The STTMRAM element, as recited in claim 1, whereinthe free layer is made of cobolt-iron-boron-Y (CoFeB-Y), where ‘Y’ ischosen from one or more of oxides and nitrides.
 8. The STTMRAM element,as recited in claim 1, wherein the free layer is made ofcobolt-iron-boron-Y (CoFeB-Y), where ‘Y’ is chosen from one or more ofthe alloys: SiO2, TiO2, Ta2O5, WO, or ZrO2.
 9. The STTMRAM element, asrecited in claim 1, wherein the first pinned layer and the second pinnedlayer in the PRL have a crystalline anisotropy in a directionperpendicular to the film plane.
 10. The STTMRAM element, as recited inclaim 1, wherein the JL is made of a material selected from a group ofnon-magnetic metals comprising: copper (Cu), silver (Ag), and gold (Au).11. The STTMRAM element, as recited in claim 1, wherein the JL is madeof a material selected from a group of non-magnetic materialscomprising: aluminum oxide (Al2O3), zinc oxide (ZnO), and magnesiumoxide (MgO).
 12. The STTMRAM element, as recited in claim 1, wherein theJL layer is a coupling layer (CL) disposed between the FL and the PRL.13. The STTMRAM element, as recited in claim 12, wherein the CL layercomprises: Ru, Cu, Ag, Au, Cr, Ti, Ta, Mn, MgO, Al2O3, NiO, TiO, SiO2,or SiN.
 14. The method of storing a state, as recited in claim 12,wherein the CL is made of metallic materials or oxides.
 15. The STTMRAMelement, as recited in claim 1, wherein the first PL and the second PLare each made of magnetic material and have perpendicular anisotropy andtheir magnetic orientation, relative to one another, is anti-parallel.16. The STTMRAM element, as recited in claim 1, wherein the TSL is madeof non-magnetic material.
 17. The STTMRAM element, as recited in claim1, wherein the TSL is made of oxide material.
 18. The STTMRAM element,as recited in claim 1, wherein the TSL is made of any of the elements:Ru, Cu, NiO, or MgO.
 19. The STTMRAM element, as recited in claim 1,wherein the TSL generates an antiferromagnetic exchange coupling betweenthe first pinned layer and the second pinned layer in the PRL.
 20. TheSTTMRAM element, as recited in claim 1, wherein the TSL has a thicknessof 0.3 nm to 5 nm.
 21. The STTMRAM element, as recited in claim 1,wherein any one of the first or the second pinned layers is made ofmultiple layers and materials selected from one or more of a group ofmaterials comprising an interlacing of a magnetic layer and anon-magnetic layer including any of: [Co/Pt]n, [Co/Pd]n, [Co/Ni]n,[CoFe/Pt]n, [CoFe/Pd]n, [CoFe/Ni]n, where ‘n’ is a positive integer anddesignates the number of repetitions of the magnetic and non-magneticinterlacing.
 22. The STTMRAM element, as recited in claim 1, wherein anyone of the first or the second pinned layer are made of an alloy thathas intrinsic perpendicular anisotropy, including any of the alloys:TbFeCo, GdFeCo, FePt, CoPt, or CoCrPt.
 23. The STTMRAM element, asrecited in claim 1, wherein at least one of the first or the secondpinned layer is made of an iron platinum alloy (FePtXY), where X and Yeach represent a material and X is a material selected from a groupcomprising of: boron (B), phosphorous (P), carbon (C), nitride (N) and Ybeing any of the materials: Cobolt (Co), tantalum (Ta), titanium (Ti),niobium (Nb), zirconium (Zr), tungsten (W), silicon (Si), copper (Cu),silver (Ag), aluminum (Al), chromium (Cr), tin (Sn), lead (Pb), antimony(Sb), hafnium (Hf) and bismuth (Bi), molybdenum (Mo), and ruthenium(Ru).
 24. A spin-transfer torque magnetic random access memory (STTMRAM)element configured to store a state when electrical current is appliedthereto, the STTMRAM element comprising: a. a fixed layer withmagnetization pinned in the plane of the fixed layer; b. a barrier layerformed on top of the fixed layer; c. a magnetization layer formed on topof the barrier layer, the magnetization layer comprising a first freelayer and a second free layer, separated by a non-magnetic separationlayer (NMSL), the first and second free layers each having in-planemagnetizations that act on each other through anti-parallel coupling; d.a perpendicular reference layer (PRL) formed on top of the magnetizationlayer with magnetization of the PRL in a direction perpendicular to themagnetization of the fixed layer, the PRL including a first pinned layer(PL) and a second pinned layer (PL) separated from one another by a topseparator layer (TSL), where the magnetization directions of the firstpinned layer and the second pinned are anti-parallel relative to eachother, the direction of the magnetization of the first and second freelayers each being in-plane prior to the application of electricalcurrent and after the application of electrical current to the STTMRAMelement, the direction of magnetization of the second free layerbecoming titled out-of-plane and the direction of magnetization of thefirst free layer switching, and upon electrical current no longerflowing through the STTMRAM element, the direction of magnetization ofthe second free layer maintaining a direction that is substantiallyopposite to that of the first free layer.
 25. The STTMRAM element, asrecited in claim 24, wherein the NMSL is an oxide composed of one ormore of the materials selected from a group consisting of: Mg, Al, B,Zn, O, N, Fe, Co, and Si.
 26. The STTMRAM element, as recited in claim24, wherein the NMSL is made of non-magnetic material.
 27. The STTMRAMelement, as recited in claim 24, wherein the NMSL is made of a materialselected from a group consisting of: titanium dioxide (TiO2), oxide(Al2O3), ruthenium oxide (RuO), strontium oxide (SrO), zinc oxide (ZnO),magnesium oxide (MgO), zirconium dioxide (ZrO2), titanium (Ti), tantalum(Ta), ruthenium (Ru), magnesium (Mg), chromium (Cr), niobium (Nb), andnickel niobium (NiNb).
 28. The STTMRAM element, as recited in claim 24,wherein the NMSL is made of ‘n’ number of interlaced non-magnetic oxideand non-magnetic metallic layers, with ‘n’ being an integer equal orgreater than one.
 29. A spin-transfer torque magnetic random accessmemory (STTMRAM) element configured to store a state when electricalcurrent is applied thereto, the STTMRAM element comprising: a. a fixedlayer with magnetization pinned in the plane of the fixed layer; b. abarrier layer formed on top of the fixed layer; c. a free layer (FL)formed on top of the barrier layer and having in-plane magnetization; d.a perpendicular reference layer (PRL) formed on top of the FL withmagnetization in a direction perpendicular to the magnetization of thefixed layer, the PRL including a first pinned layer (PL) and a secondpinned layer (PL) separated from one another by a top separator layer(TSL), where the magnetization directions of the first pinned layer andthe second pinned are anti-parallel relative to each other, thedirection of the magnetization of the FL being in-plane prior to theapplication of electrical current.
 30. The STTMRAM element, as recitedin claim 29, wherein the free layer comprises one or multiple elementsCo, Fe, or Ni.
 31. The STTMRAM element, as recited in claim 29, whereinthe free layer further comprises one or more of the elements: B, Ta, Ti,Cr, Hf, Zr, O, Mg, Al, Ru, W, Mn, Si, Pt, Mn, or Pd.
 32. The STTMRAMelement, as recited in claim 30, wherein the free layer is made ofcobolt-iron-boron-X (CoFeB-X), where ‘X’ is chosen from among a group ofelements having low emissivity into Co and/or Fe.
 33. The STTMRAMelement, as recited in claim 30, wherein the free layer is made ofcobolt-iron-boron-X (CoFeB-X), where ‘X’ is one or more of the elements:Cr, Cu, Ta, Ti, Mo, P, N, or O.
 34. The STTMRAM element, as recited inclaim 29, wherein the free layer comprises a multi-layer structure withat least one magnetic layer and wherein the at least one magnetic layercomprising at least one of the elements: Co, Fe, or Ni.
 35. The STTMRAMelement, as recited in claim 29, wherein the free layer is made ofcobolt-iron-boron-Y (CoFeB-Y), where ‘Y’ is chosen from one or more ofthe oxides and nitrides.
 36. The STTMRAM element, as recited in claim29, wherein the free layer is made of cobolt-iron-boron-Y (CoFeB-Y),where ‘Y’ is chosen from one or more of the alloys: SiO2, TiO2, Ta2O5,WO, or ZrO2.
 37. The STTMRAM element, as recited in claim 29, whereinthe first pinned layer and second pinned layer in the PRL have acrystalline anisotropy in the direction perpendicular to the film plane.38. The STTMRAM element, as recited in claim 29, wherein the first PLand the second PL are each made of magnetic material and haveperpendicular anisotropy and their magnetic orientation, relative to oneanother, is anti-parallel.
 39. The STTMRAM element, as recited in claim29, wherein the TSL is made of non-magnetic material.
 40. The STTMRAMelement, as recited in claim 29, wherein the TSL is made of oxidematerial.
 41. The STTMRAM element, as recited in claim 29, wherein theTSL generates an antiferromagnetic exchange coupling between the firstpinned layer and the second pinned layer in the PRL.
 42. The STTMRAMelement, as recited in claim 29, wherein the TSL is made of anon-magnetic material selected from any of the elements: ruthenium (Ru),copper (Cu), tantalum (Ta), titanium (Ti), or nickel oxide (NiO). 43.The STTMRAM element, as recited in claim 29, wherein the TSL is made ofmagnesium oxide (MgO).
 44. The STTMRAM element, as recited in claim 29,wherein the TSL has a thickness of 0.3 nm to 5 nm.
 45. The STTMRAMelement, as recited in claim 29, wherein any one of the first or thesecond pinned layers are made of multiple layers comprising aninterlacing of a magnetic layer and a non-magnetic layer comprising:[Co/Pt]n, [Co/Pd]n, [Co/Ni]n, [CoFe/Pt]n, [CoFe/Pd]n, [CoFe/Ni]n, where‘n’ is a positive integer and designates the number of repeats of themagnetic and non-magnetic interlacing.
 46. The STTMRAM element, asrecited in claim 29, wherein any one of the first or the second pinnedlayer are made of an alloy that has intrinsic perpendicular anisotropyand comprising: TbFeCo, GdFeCo, FePt, CoPt, or CoCrPt.
 47. The STTMRAMelement, as recited in claim 29, wherein at least one of the first orthe second pinned layer is made of an iron platinum alloy (FePtXY),where X and Y each represent a material and X is a material selectedfrom a group consisting of: boron (B), phosphorous (P), carbon (C),nitride (N) and Y being any of the materials: Cobolt (Co), tantalum(Ta), titanium (Ti), niobium (Nb), zirconium (Zr), tungsten (W), silicon(Si), copper (Cu), silver (Ag), aluminum (Al), chromium (Cr), tin (Sn),lead (Pb), antimony (Sb), hafnium (Hf), bismuth (Bi), molybdenum (Mo),and ruthenium (Ru).
 48. The STTMRAM element, as recited in claim 1,wherein the barrier layer is made of a material selected from a group ofnon-magnetic materials comprising: aluminum oxide (Al2O3), zinc oxide(ZnO), and magnesium oxide (MgO).
 49. The STTMRAM element, as recited inclaim 24, wherein the barrier layer is made of a material selected froma group of non-magnetic materials comprising: aluminum oxide (Al2O3),zinc oxide (ZnO), and magnesium oxide (MgO).
 50. The STTMRAM element, asrecited in claim 29, wherein the barrier layer is made of a materialselected from a group of non-magnetic materials comprising: aluminumoxide (Al2O3), zinc oxide (ZnO), and magnesium oxide (MgO).